Method and apparatus for depositing films

ABSTRACT

The disclosure relates to a method for depositing films on a substrate which may form part of an LED or other types of display. In one embodiment, the disclosure relates to an apparatus for depositing ink on a substrate. The apparatus includes a chamber for receiving ink; a discharge nozzle having an inlet port and an outlet port, the discharge nozzle receiving a quantity of ink from the chamber at the inlet port and dispensing the quantity of ink from the outlet port; and a dispenser for metering the quantity of ink from the chamber to the inlet port of the discharge nozzle; wherein the chamber receives ink in liquid form having a plurality of suspended particles and the quantity of ink is pulsatingly metered from the chamber to the discharge nozzle; and the discharge nozzle evaporates the carrier liquid and deposits the solid particles on the substrate.

This instant application is a divisional application of U.S.Non-Provisional Application Ser. No. 12/139,391, filed on Jun. 13, 2008,PCT Application No. PCT/US2008/066975, filed on Jun. 13, 2008, andclaims priority U.S. Provisional Application Ser. No. 60/944,000 filedon Jun. 14, 2007.

BACKGROUND

1. Field of the Invention

The disclosure relates to a method and apparatus for efficientlydepositing patterns of films on a substrate. More specifically, thedisclosure relates to a method and apparatus for depositing films on asubstrate which may form part of an LED or other types of display.

2. Description of the Related Art

The manufacture of organic light emitting devices (OLEDs) requiresdepositing one or more organic films on a substrate and coupling the topand bottom of the film stack to electrodes. The film thickness is aprime consideration. The total layer stack thickness is about 100 nm andeach layer is optimally deposited uniformly with an accuracy of betterthan +/−1 nm. Film purity is also important. Conventional apparatusesform the film stack using one of two methods: (1) thermal evaporation oforganic material in a relative vacuum environment and subsequentcondensation of the organic vapor on the substrate; or, (2) dissolutionof organic material into a solvent, coating the substrate with theresulting solution, and subsequent removal of the solvent.

Another consideration in depositing the organic thin films of an OLED isplacing the films precisely at the desired location. There are twoconventional technologies for performing this task, depending on themethod of film deposition. For thermal evaporation, shadow masking isused to form OLED films of a desired configuration. Shadow maskingtechniques require placing a well-defined mask over a region of thesubstrate followed by depositing the film over the entire substratearea. Once deposition is complete, the shadow mask is removed. Theregions exposed through the mask define the pattern of materialdeposited on the substrate. This process is inefficient, as the entiresubstrate must be coated, even though only the regions exposed throughthe shadow mask require a film. Furthermore, the shadow mask becomesincreasingly coated with each use, and must eventually be discarded orcleaned. Finally, the use of shadow masks over large areas is madedifficult by the need to use very thin masks (to achieve small featuresizes) that make said masks structurally unstable. However, the vapordeposition technique yields OLED films with high uniformity and purityand excellent thickness control.

For solvent deposition, ink jet printing can be used to deposit patternsof OLED films. Ink jet printing requires dissolving organic materialinto a solvent that yields a printable ink. Furthermore, ink jetprinting is conventionally limited to the use of single layer OLED filmstacks, which typically have lower performance as compared to multilayerstacks. The single-layer limitation arises because printing typicallycauses destructive dissolution of any underlying organic layers.Finally, unless the substrate is first prepared to define the regionsinto which the ink is to be deposited, a step that increases the costand complexity of the process, ink jet printing is limited to circulardeposited areas with poor thickness uniformity as compared to vapordeposited films. The material quality is also typically lower, due tostructural changes in the material that occur during the drying processand due to material impurities present in the ink. However, the ink jetprinting technique is capable of providing patterns of OLED films oververy large areas with good material efficiency.

No conventional technique combines the large area patterningcapabilities of ink jet printing with the high uniformity, purity, andthickness control achieved with vapor deposition for organic thin films.Because ink jet processed single layer OLED devices continue to haveinadequate quality for widespread commercialization, and thermalevaporation remains impractical for scaling to large areas, it is amajor technological challenge for the OLED industry to develop atechnique that can offer both high film quality and cost-effective largearea scalability.

Finally, manufacturing OLED displays may also require the patterneddeposition of thin films of metals, inorganic semiconductors, and/orinorganic insulators. Conventionally, vapor deposition and/or sputteringhave been used to deposit these layers. Patterning is accomplished usingprior substrate preparation (e.g., patterned coating with an insulator),shadow masking as described above, and when a fresh substrate orprotective layers are employed, conventional photolithography. Each ofthese approaches is inefficient as compared to the direct deposition ofthe desired pattern, either because it wastes material or requiresadditional processing steps. Thus, there is a need for these materialsas well for a method and apparatus for depositing high-quality, costeffective, large area scalable films.

SUMMARY

In one embodiment, the disclosure is directed to an apparatus fordepositing ink on a substrate, the apparatus comprising: a chamber forreceiving ink; a discharge nozzle having an inlet port and an outletport, the discharge nozzle receiving a quantity of ink from the chamberat the inlet port and dispensing the quantity of ink from the outletport; and a dispenser for metering the quantity of ink from the chamberto the inlet port of the discharge nozzle; wherein the chamber receivesink in liquid form having a plurality of suspended particles and thequantity of ink is pulsatingly metered from the chamber to the dischargenozzle; and the discharge nozzle evaporates the carrier liquid anddeposits the substantially solid particles on the substrate.

In another embodiment, the disclosure relates to a method for depositingink on a substrate, the method comprising: using a pulsating energyhaving a first frequency to meter a quantity of ink to a dischargenozzle, the ink defined by a plurality of solid particles in a carrierliquid; receiving the metered quantity of ink at the discharge nozzleand evaporating the carrier liquid from the metered quantity of ink toprovide a quantity of substantially solid ink particles; dispensing thesubstantially solid ink particles from the discharge nozzle anddepositing the substantially solid ink particles on the substrate; andwherein at least a portion of the substantially solid ink particles areconverted to a vapor phase during discharge from the discharge nozzle,directed to the substrate as a vapor, and condense on a surface of thesubstrate in substantially solid form.

In still another embodiment, the disclosure relates to a method fordepositing ink on a substrate, the method comprising: providing liquidink to a chamber, the liquid ink defined by a plurality of suspendedparticles in a carrier liquid; pulsatingly energizing a dispenser tometer a quantity of liquid ink from the chamber to a discharge nozzle,the quantity of liquid ink metered as a function of a frequency of atleast one of a pulse amplitude, a pulse duration or a pulse frequency;receiving the metered quantity of ink at a discharge nozzle, thedischarge nozzle having a plurality of conduits for directing themetered quantity of ink; heating the metered quantity of ink at theplurality of conduits to evaporate the carrier liquid; and dischargingthe plurality of suspended particles from the discharge nozzle onto thesubstrate; wherein the plurality of suspended particles are deposited onthe substrate in substantially solid form.

In still another embodiment, the disclosure relates to a system fordepositing ink on a substrate, the system comprising: a chamber having aquantity of ink, the ink defined by a plurality of suspended inkparticles in a carrier liquid; a discharge nozzle proximal to thechamber for receiving a metered quantity of ink pulsatingly deliveredfrom the chamber by a dispenser, the discharge nozzle evaporating thecarrier liquid to form a substantially solid quantity of ink particles;and a controller in communication with the discharge nozzle, thecontroller energizing the discharge nozzle to communicate thesubstantially solid quantity of ink particles from the discharge nozzleonto the substrate.

In still another embodiment, the disclosure relates to a system fordepositing ink on a substrate, the system comprising: a chamber forreceiving a quantity of ink, the ink having a plurality of suspendedparticles in a carrier liquid; an ink dispenser for pulsatingly meteringa quantity of ink delivered from the chamber; a discharge nozzle forreceiving a metered quantity of ink delivered from the chamber andevaporating the carrier liquid from the received quantity of ink to forma substantially solid quantity of particles; a first controller incommunication with the ink dispenser, the first controller pulsatinglyenergizing the dispenser to meter a quantity of ink delivered from thechamber; and a second controller in communication with the dischargenozzle, the second controller energizing the discharge nozzle tocommunicate the metered quantity of particles from the discharge nozzleonto the substrate.

In still another embodiment, the disclosure relates to a method forproviding accurate deposition of ink on a substrate, the methodcomprising: providing a quantity of ink to a chamber, the ink having aplurality of suspended particles in a carrier liquid; metering at leasta portion of the ink delivered from the chamber to an inlet of adischarge nozzle by activating a dispenser; receiving the metered ink ata discharge nozzle, the discharge nozzle having an inlet port and anoutlet port; transporting the metered ink from the inlet port to theoutlet port of the discharge nozzle forming substantially solidparticles; and depositing the substantially solid particles from theoutlet port of the discharge nozzle onto a substrate by energizing thedischarge nozzle to pulsatingly eject at least a portion of thesubstantially solid particles onto the substrate.

In yet another embodiment, the disclosure relates to a system foraccurate deposition of ink on a substrate, the system comprising: astorage means for storing a composition of ink particles in a carrierliquid; a metering means in communication with the storage means topulsatingly meter at least a portion of the composition; a transportingmeans for transporting the ink from the chamber to a discharge nozzle;an evaporating means for evaporating the carrier liquid to form asubstantially solid quantity of ink particles at the discharge nozzle;and a discharging means for discharging the substantially solid inkparticles from the discharge nozzle onto a substrate.

In still another embodiment, the disclosure relates to an apparatus fordepositing particles on a substrate, the apparatus comprising: a chamberfor receiving ink, the chamber receiving ink in liquid form having aplurality of particles in a carrier liquid; a dispenser associated withthe chamber, the dispenser metering a quantity of ink delivered from thechamber to a discharge nozzle, the discharge nozzle evaporating thecarrier liquid to form a substantially solid quantity of ink particles;wherein the discharge nozzle rotates axially relative to the chamber todischarge the substantially solid quantity of ink particles; and whereinthe discharge nozzles deposits the substantially solid particles onto asubstrate.

In still another embodiment, the disclosure relates to a system forcontrolling a printing device, the system comprising: a first controllerhaving a first processor circuit in communication with a first memorycircuit, the first memory circuit containing instructions for directingthe first processor to: identify a plurality of chambers, each chamberreceiving liquid ink having a plurality of dissolved or suspendedparticles in a carrier liquid, engage each of the plurality of chambersto meter a quantity of liquid ink for dispensing; a second controllerhaving a second processor circuit in communication with a second memorycircuit, the second memory circuit containing instructions for directingthe second processor to: identify a plurality of discharge nozzles, eachof the plurality of discharge nozzles receiving the quantity of liquidfrom a corresponding one of the plurality of chambers, activate each ofthe plurality of the discharge nozzles to evaporate at least a part ofthe carrier liquid, direct each of the plurality of discharge nozzles todeposit substantially solid ink particles onto a substrate.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other embodiments of the disclosure will be discussed withreference to the following non-limiting and exemplary illustrations, inwhich like elements are numbered similarly, and where:

FIG. 1A is a schematic representation of an exemplary print-head havinga thermal ink dispensing mechanism according to one embodiment of thedisclosure;

FIG. 1B is a schematic representation of an exemplary print-head havinga piezoelectric ink dispensing mechanism according to one embodiment ofthe disclosure;

FIG. 1C is a schematic representation of an exemplary print-head havingphysically separated chamber housing and discharge nozzle housingportions according to one embodiment of the disclosure;

FIG. 1D is a schematic representation of an exemplary print-head havingphysically separated chamber housing and discharge nozzle housingportions, and isolation space between the discharge nozzle and theassociated housing, according to one embodiment of the disclosure;

FIG. 1E shows a top view of an exemplary implementation of the dischargenozzle;

FIGS. 2A-2D schematically illustrate the process of depositing asolvent-free material using a print-head apparatus according to anembodiment of the disclosure;

FIG. 3A schematically illustrates a print-head apparatus having multipledischarge nozzles and using thermal ink dispensing elements;

FIG. 3B schematically illustrates a print-head apparatus having multipledischarge nozzles and using piezoelectric ink dispensing elements;

FIG. 4 is a schematic representation of a print-head apparatus withmultiple reservoirs;

FIG. 5 schematically illustrates an apparatus for depositing thin filmsof material using one or more print-heads, at least one of which havingone or more discharge nozzles, and a positioning system;

FIG. 6 schematically illustrates a micro-porous discharge nozzle havingmicro-pores with tapered sidewalls;

FIG. 7 shows exemplary micro-pore patterns for use in a micro-porousdischarge nozzle;

FIGS. 8A and 8B (collectively, FIG. 8) schematically illustrate a dyesublimation printer in accordance with one embodiment of the disclosure;

FIGS. 9A and 9B illustrate the use of the discharge apparatus forspatially localized chemical synthesis;

FIGS. 9C and 9D depict the use of a discharge apparatus as a microreactor;

FIG. 10A is a schematic representation of an exemplary print-head inaccordance with an embodiment of the disclosure;

FIGS. 10B-10E illustrate a method for depositing a film using theprint-head shown in FIG. 10A;

FIG. 11A schematically illustrates a thermally activated print-headaccording to one embodiment of the disclosure;

FIGS. 11B-11E illustrate a method for depositing a film using theprint-head apparatus shown in FIG. 11A;

FIG. 12 illustrates a method for depositing particles on a substrateaccording to one embodiment of the disclosure; and

FIG. 13 is a schematic representation of a control system forcontrolling a print-head having a discharge nozzle, according to oneembodiment of the disclosure.

DETAILED DESCRIPTION

In one embodiment, the disclosure relates to a method and apparatus fordepositing a film in substantially solid form on a substrate. Such filmscan be used, for example, in the design and construction of OLEDs andlarge area transistor circuits. In one embodiment, the disclosurerelates to a method and apparatus for depositing a film of material insubstantially solid form on a substrate. In another embodiment, thedisclosure relates to a method and apparatus for depositing a film ofmaterial substantially free of solvent of a substrate. Such films can beused, for example, in the design and construction of OLEDs and largearea transistor circuits. The materials that may be deposited by theapparatuses and methods described herein include organic materials,metal materials, and inorganic semiconductors and insulators, such asinorganic oxides, chalcogenides, Group IV semiconductors, Group III-Vcompound semiconductors, and Group II-VI semiconductors.

FIG. 1A is a schematic representation of an apparatus for depositingmaterial according to one embodiment of the disclosure. Namely, FIG. 1Aprovides a schematic representation of a thermal jet print-headaccording to one embodiment of the disclosure.

Referring to FIG. 1A, the exemplary apparatus for depositing a materialon a substrate comprises chamber 130, orifice 170, nozzle 180, andmicro-porous conduits 160. Chamber 130 receives ink in liquid form andcommunicates the ink from orifice 170 to discharge nozzle 180. The inkcan comprise suspended or dissolved particles in a carrier liquid. Theseparticles can comprise single molecules or atoms, or aggregations ofmolecules and/or atoms. The path between orifice 170 and dischargechamber 180 defines a delivery path. In the embodiment of FIG. 1A,discharge nozzle 180 comprises conduits 160 separated by partitions 165.Conduits 160 may include micro-porous material therein. A surface ofdischarge nozzle 180 proximal to orifice 170 defines the inlet port todischarge nozzle 180 while the distal surface of discharge nozzle 180defines the outlet port. A substrate (not shown) can be positionedproximal to the outlet port of discharge nozzle 180 for receiving inkdeposited from the nozzle.

The thermal jet print-head of FIG. 1 further includes bottom structure140, which receives discharge nozzle 180. Discharge nozzle 180 can befabricated as part of the bottom structure 140. Alternatively, dischargenozzle 180 can be manufactured separately and later combined with bottomstructure 140 to form an integrated structure. Top structure 142receives chamber 130. Top structure 142 can be formed with appropriatecavities and conduits to form chamber 130. Top structure 142 and bottomstructure 140 are coupled through bonds 120 to form a housing. Thehousing allows the thermal jet print-head to operate under pressure orin vacuum. The housing may further comprise an inlet port (not shown)for accepting a transport gas for carrying the material from thedischarge nozzle to the substrate (not shown). Alternatively, a port(not shown) can be integrated into top structure 142 to receivetransport gases. The port can include a flange adapted to receive atransport gas, which according to one embodiment comprises asubstantially inert mixture of one or more gases. The mixture caninclude gases which are substantially non-reactive with the materialsbeing deposited by the apparatus, such as nitrogen or argon when usedwith typical organic materials. The transport gas can transportparticles from discharge nozzle 180 by flowing through micro-pores 160.

A heater 110 can be added optionally to chamber 130 for heating and/ordispensing the ink. In FIG. 1A, heater 110 is positioned inside chamber130. Heater 110 can be any thermal energy source coupled to chamber 130for providing pulsating energy to the liquid ink and thereby discharge adroplet of the liquid ink through orifice 170. In one embodiment, heater110 delivers heat in pulses having a duration of one minute or less. Forinstance, the heater can be energized with square pulses having avariable duty cycle and a cycle frequency of 1 kHz. Thus, the heaterenergy can be used to meter the quantity of ink delivered from chamber130 to discharge nozzle 180. Chamber 130 may also contain material,other than ink, required for forming a film used in the fabrication ofan OLED or transistor. Orifice 170 can be configured such that surfacetension of the liquid in chamber 130 prevents discharge of the liquidprior to activation of the mechanism for dispensing the ink.

In the embodiment of FIG. 1A, discharge nozzle 180 includes partitions(or rigid portions) 165 separated by conduits 160. Conduits 160 andrigid portions 165 can collectively define a micro porous environment.The micro-porous environment can be composed of a variety of materials,including, micro-porous alumina or solid membranes of silicon or siliconcarbide and having micro-fabricated pores. Micro-pores 160 prevent thematerial dissolved or suspended in the liquid from escaping throughdischarge nozzle 180 until the medium is appropriately activated. Whenthe discharged droplet of liquid encounters discharge nozzle 180, theliquid is drawn into micro-pores 160 with assistance from capillaryaction. The liquid in the ink may evaporate prior to activation ofdischarge nozzle 180, leaving behind a coating of the suspended ordissolved particles on the micro-pore walls. The liquid in the ink maycomprise one or more solvents with a relatively-low vapor pressure. Theliquid in the ink may also comprise one or move solvents with arelatively-high vapor pressure.

The evaporation of the liquid in the ink may be accelerated by heatingthe discharge nozzle. The evaporated liquid can be removed from thechamber and subsequently collected (not shown), for instance, by flowinggas over one or more of the discharge nozzle faces. Depending on thedesired application, micro-pores 160 can provide conduits (or passages)having a maximum linear cross-sectional distance W of a few nanometersto hundreds of microns. The micro-porous region comprising dischargenozzle 180 will take a different a shape and cover a different areadepending on the desired application, with a typical maximum linearcross-sectional dimension D ranging from a few hundred nanometers totens of millimeters. In one embodiment, the ratio of W/D is in a rangeof about 1/10 to about 1/1000.

In the exemplary apparatus of FIG. 1A, discharge nozzle 180 is actuatedby nozzle heater 150. Nozzle heater 150 is positioned proximal todischarge nozzle 180. Nozzle heater 150 may comprise a thin metal film.The thin metal film can be comprised of, for example, platinum. Whenactivated, nozzle heater 150 provides pulsating thermal energy todischarge nozzle 180, which acts to dislodge the material containedwithin micro-pores or conduits 160, which can subsequently flow out fromthe discharge nozzle. In one embodiment, the pulsations can be variableon a time scale of one minute or less.

Dislodging the ink particles may include vaporization, either throughsublimation or melting and subsequent boiling. It should be noted againthat the term particles is used generally, and includes anything from asingle molecule or atom to a cluster of molecules or atoms. In general,one can employ any energy source coupled to the discharge nozzle that iscapable of energizing discharge nozzle 180 and thereby discharging thematerial from micro-pores 160; for instance, mechanical (e.g.,vibrational). In one embodiment of the disclosure, a piezoelectricmaterial is used instead of, or in addition to, nozzle heaters 150.

FIG. 1B is a schematic representation of an apparatus for depositing afilm according to one embodiment of the disclosure. Referring to FIG.1B, the exemplary apparatus for depositing a material on a substrate issimilar to the embodiment of FIG. 1A, except chamber 130 is shapeddifferently, and the ink is dispensed by pulsatingly activatingpiezoelectric element 115. When activated, piezoelectric elements 115pulsate to discharge a droplet of the liquid contained within chamber130 through orifice 170 toward discharge nozzle 180. Thus, chamberheater 110 can be replaced by piezoelectric elements 115. While notshown in FIG. 1B, the piezoelectric elements can be used in addition toor in combination with a chamber heater.

FIG. 1C is a schematic representation of an apparatus for depositing afilm according to another embodiment of the disclosure. Referring toFIG. 1C, the exemplary apparatus for depositing a material on asubstrate comprises similar elements as in FIG. 1B except bonds 120 areremoved to illustrate that top structure 142 and bottom structure 140can be structurally distinct components. In the configuration of FIG.1C, top structure 142 and bottom structure 140 may be accessed andpositioned independently, as may be desirable when performingmaintenance on the apparatus.

FIG. 1D is a schematic representation of an apparatus for depositing afilm according to still another embodiment of the disclosure. Theexemplary apparatus of FIG. 1D comprises similar elements as theapparatus of FIG. 1C except confining well 145 is introduced. Thisstructure mechanically confines ink, or any other material, supplied todischarge nozzle 180 from ink chamber 130 through chamber orifice 170.This structure can enhance the uniformity of the loading of ink intomicro-pores 160 and can correct for positioning errors in the placementof ink material supplied to discharge nozzle 180 from ink chamber 130.

Another distinction in the embodiment of FIG. 1D is the presence ofconnective regions 155. In each of FIGS. 1A to 1C, discharge nozzle 180was shown as integrated with the bottom structure 140. In contrast,discharge nozzle 180 of FIG. 1D is manufactured to achieve a physicallydistinct bottom structure 140 and discharge nozzle 180 with connectiveregions 155 comprising a different material. Regions 155 are used toconnect discharge nozzle 180 to bottom structure 140. Connective regions155 extend beyond bottom structure 140 to leave opening 156. Opening 156can be adjusted depending on the size of the housing and the objectivesin physically separating 180 from 140. For instance, this configurationcan provide improved thermal isolation of discharge nozzle 180 from thesurrounding structure. FIG. 1D also shows heater 150 extending beneathbrackets 155 to reach discharge nozzle 180. It should be noted thatheater 150 can be replaced augmented by or replaced with a piezoelectricelement or other electromechanical means for delivering pulsatingenergy.

FIG. 1E is an image of a discharge nozzle 180, as part of an apparatusfor depositing a film on a substrate. In FIG. 1E, discharge nozzleheater 150 is comprised of a thin platinum film on a silicon housing140. In the center of discharge nozzle 180 are also shown dischargenozzle micro-pores corresponding to micro-pores 160 indicated in priorfigures.

FIGS. 2A-2D schematically show the process of depositing ink on asubstrate according to one embodiment of the disclosure. While differentfilms and material can be deposited using the embodiments disclosedherein, in one embodiment, the ink is deposited in substantially solidform. In FIG. 2A, ink 101 is commissioned to chamber 130. Ink 101 canhave a conventional composition. In one embodiment, ink 101 is a liquidink defined by a plurality of particles in a carrier liquid. The carrierliquid can comprise one or more solvents having a vapor pressure suchthat during the transportation and deposition process the solvent issubstantially evaporated and the plurality of particles in the carrierliquid are deposited as solid particles. Thus, the deposited pluralityof solid particles are deposited comprise a film on the substrate.

Referring again to FIG. 2A, chamber heater 110 comprises the inkdispensing mechanism and pulsatingly imparts thermal energy into ink101. The thermal energy drives at least a portion of ink liquid 101through orifice 170 to form ink droplet 102. Ink droplet 102 can defineall of, or a portion of liquid ink 101. The pulsating impartment ofenergy from an energy source (e.g., heater 110) determines the quantityof ink to be metered out from chamber 130. Once droplet 102 is meteredout of chamber 130, it is directed to discharge nozzle 180.

In another exemplary embodiment, piezoelectric elements (not shown) canbe positioned at or near chamber 130 to meter out the desired quantityof ink 101 through orifice 170, thereby forming droplet 101. In yetanother exemplary embodiment, liquid can be streamed out of chamber 130through orifice 170 (by, for instance, maintaining a positive inkpressure) and this stream can be pulsatingly interrupted by a mechanicalor electrostatic force such that metered droplets created from thisstream and further directed onto discharge nozzle 180. If a mechanicalforce is utilized, this force can be provided by introducing a paddle(not shown) that pulsatingly intersects the stream. If an electrostaticforce is utilized, this force can be provided by introducing a capacitor(not shown) around the stream that pulsatingly applies anelectromagnetic field across the stream. Thus, any pulsating energysource that activates a dispensing mechanism and thereby meters liquid102 delivered from chamber 130 through orifice 170 and to dischargenozzle 180 can be utilized. The intensity and the duration of eachenergy pulse can be defined by a controller (not shown) which isdiscussed below. Furthermore, as noted above, this metering can occurprimarily when the ink is ejected from chamber 130 through orifice 170;alternatively, this metering can occur primarily wile the ink istraveling from orifice 170 to discharge nozzle 180.

As discussed in relation to FIGS. 1A-1E, discharge nozzle 180 includesconduits for receiving and transporting metered droplet 102. Dischargenozzle heater 150 is placed proximal to discharge nozzle 180 to heat thedischarge nozzle. In an exemplary embodiment (not shown), a heater isintegrated with the discharge nozzle such that partitions 165 define theheating elements.

Discharge nozzle 180 has a proximal surface (alternatively, inlet port)181 and a distal surface (alternatively, outlet port) 182. Proximalsurface 181 and distal surface 182 are separated by a plurality ofpartitions 160 and conduits 165. Proximal surface 181 faces chamber 130and distal surface 182 faces substrate 190. Nozzle heater 150 can beactivated such that the temperature of discharge nozzle 180 exceeds theambient temperature which enables rapid evaporation of the carrierliquid from droplet 102 which is now lodged in conduits 160. Nozzleheater 150 may also be activated prior to energizing the ink dispenser(and metering ink droplet 102 as it travels from chamber 130 throughorifice 170 to discharge nozzle 180) or after droplet 102 lands ondischarge nozzle 180. In other words, chamber heater 110 and dischargeheater 150 can be choreographed to pulsate simultaneously orsequentially.

In the next step of the process, liquid ink 103 (previously droplet 102)is directed to inlet port 181 of discharge nozzle 180 between confiningwalls 145. Liquid ink 103 is then drawn through conduits 160 towardoutlet port 182. As discussed, conduits 160 can comprise a plurality ofmicro-pores. Liquid in ink 103, which may fill conduits 160 extends ontothe surrounding surface, with the extent of this extension controlled inpart by the engineering of confining walls 145, may evaporate prior toactivation of discharge nozzle 180, leaving behind on the micro-porewalls the particles 104 (FIG. 2C) that are substantially solid and whichcan be deposited onto substrate 190. Alternatively, the carrier liquidin ink 103 (FIG. 2B) may evaporate during activation of nozzle heater150.

Activating nozzle heater 150 in FIG. 2C, provides pulsating energy todischarge nozzle 180 and dislodges material 104 from conduits 160. Theresult is shown in FIG. 2D. The intensity and the duration of eachenergy pulse can be defined by a controller (not shown.) The activatingenergy can be thermal energy. Alternatively, any energy source directedto discharge nozzle 180 which is capable of energizing discharge nozzle180 to thereby discharge material 104 from conduits 160 (e.g.,mechanical, vibrational, ultrasonic, etc.) can be used. Deposited film105 is thus deposited in solid form substantially free of the carrierliquid present in ink 101 (FIG. 2A). That is, substantially all of thecarrier liquid is evaporated from ink 103 while it travels throughdischarge nozzle 180. The evaporated carrier liquid, which typicallycomprises a mixture of one or more solvents, can be transported awayfrom the housing by one or more gas conduits (not shown).

Substrate 190 is positioned proximal to discharge nozzle 180 forreceiving the dislodged material to form thin film 105. Simultaneouswith steps shown in FIGS. 2B-2D, chamber 130 is provided with a newquantity of liquid ink 101 for the next deposition cycle.

FIG. 3A illustrates a discharge array using a heating element fordepositing material. The apparatus of FIG. 3A, includes chamber 330 forhousing liquid 301. Liquid 301 can comprise dissolved or suspendedparticles for deposition on a substrate. Chamber 330 also includes aplurality of chamber orifices 370. The embodiment of FIG. 3A comprisesink dispensing heaters 310 for pulsatingly metering liquid ink througheach chamber orifice 370 and towards discharge nozzles 380. Dischargenozzles 380 are arranged in an array such that each discharge nozzle 380communicates with a corresponding chamber orifice 370. Nozzle heaters350 are positioned near discharge nozzles 380 to evaporate substantiallyall of the carrier liquid and to allow solid particles to be depositedby the discharge nozzle array.

FIG. 3B illustrates a discharge array using a piezoelectric element.Specifically, FIG. 3B shows piezoelectric ink dispensing elements 315that pulsatingly meter out liquid ink 301 through chamber orifices 370and toward discharge nozzles 380. In general, any energy source capableof metering the ink can be used. Discharge nozzles 380 are also providedwith nozzle heaters 350. While not shown in FIGS. 3A and 3B, liquid inkis delivered to chamber 330 through one or more conduits in fluidcommunication with an ink reservoir. Additionally, one or more gasconduits (not shown) can be configured to remove any vaporized carrierliquid from the housing. In operation, piezoelectric elements 315 areenergized in bursts or pulses. With each pulse of energy, piezoelectricelements vibrate and dispense liquid ink 301 which is held in placethrough its molecular forces and surface tension. The duration of thepulse energizing piezoelectric elements 370 can determine the quantityof liquid ink 370 which is metered out from each chamber orifice 370.Thus, increasing the amplitude or the duration of, for example, a squarepulse, can increase the quantity of the dispensed liquid ink. Theviscosity or thixotropic properties of the chosen ink will impact thepulse shape, amplitude and duration for a metered quantity of ink to bedelivered from chamber 330 to discharge nozzle 380.

In FIGS. 3A and 3B, discharge nozzles 380 include micro-porous openings,intervening rigid regions, and heaters 350. The exemplary apparatus mayalso include a housing configured for operation in a vacuum or apressurized environment. The housing can further include an inlet portfor receiving a transport gas which carries the material from thedischarge nozzle 380 to the substrate (not shown). The inlet port can bedefined by a flange adapted to receive a transport gas, which accordingto one embodiment comprises a substantially inert mixture of one or moregases, such as nitrogen or argon. Nitrogen and argon are particularlysuitable when depositing conventional organic materials. The transportgas may also transport the ink from the discharge nozzles 380 by flowingthrough the conduits or the micro-pores. It should be noted that theembodiments shown in FIGS. 3A and 3B define the integration of multipleapparatus, or nozzles (shown in FIGS. 1A and 1B) to form a multi-nozzledeposition system, or a print-head, and that each individual nozzle caninclude all the features and elements described in reference to theapparatus of FIGS. 1A-1E.

Also, in the embodiments of FIGS. 3A and 3B, the chamber energy sourcesand discharge nozzles energy sources may be independently and/orsimultaneously pulsatingly activated, with the intensity and theduration of each pulse defined by a controller (not shown.) It can be animportant consideration when using the deposition apparatus of FIGS. 3Aand 3B to utilize multiple simultaneously and independently activateddischarge nozzles.

FIG. 4 is a schematic representation of a print-head apparatus withmultiple reservoirs. FIG. 4 includes reservoirs 430, 431 and 423. Eachreservoir contains a different deposition liquid. Thus, reservoir 430contains liquid ink 401, reservoir 431 contains ink 402 and reservoir432 contains ink 403. In addition, reservoir 401 communicates withchambers 410 and 412, reservoir 402 communicates with chambers 413 and414, while reservoir 403 communicates with chambers 415, 416 and 417. Inthis manner, different material can be printed simultaneously using asingle print-head. For example, liquids 401, 402 and 403 may contain theOLED materials that determine the emission color, such that liquid 401may contain the material for fabricating red OLEDs, liquid 402 maycontain the material for fabricating green OLEDs, and liquid 403 maycontain the material for fabricating blue OLEDs. Each of chambers 410,412, 413, 414, 415, 416 and 417 communicates with the respectivedischarge nozzle 440, 442, 443, 444, 445, 446 and 447.

FIG. 5 illustrates an apparatus for depositing thin films of materialusing one or more micro-porous print-heads and a positioning system.Print-head unit 530 may comprise one or more of the apparatusesdiscussed in relation to FIGS. 1A-1D or permutations thereof as shown inFIGS. 3-4. Print-head unit 530 of FIG. 5 can be connected to positioningsystem 520, which can adjust the distance between print-head unit 530and substrate 540 by traveling along guide 522. In one embodiment,print-head unit 530 is rigidly connected to positioning system 520.Print-head unit 530, positioning system 520, and guide 522 can becollectively (and optionally, rigidly) connected to positioning system510, which can adjust the position of print-head unit 530 relative tosubstrate 540 in the plane of substrate 540. The position adjustmentsperformed by positioning system 510 may be accomplished by travel alongguides 523 and 521. The exemplary apparatus of FIG. 5 may furthercomprise combinations of multiple independent print-head units andpositioning systems (not shown). In the apparatus of FIG. 5, thelocation of the substrate can be fixed. A related apparatus can beconstructed in which the print-head unit position would be fixed and thesubstrate would move relative to the print-head. Yet another relatedapparatus can be constructed in which both the print-head unit andsubstrate move simultaneously and relative to each other.

Including a motion system with the multi-nozzle micro-porous print-headhas practical advantages as it provides for high speed printing ofarbitrary patterns. The positioning systems utilized in the apparatus ofFIG. 5 may control the distance between print head unit 530 andsubstrate 540 so that the distance is between 1 micron and 1 cm. Othertolerances can be designed without departure form the principlesdisclosed herein. A control system may actively maintain a constantseparation distance, and may utilize optical or capacitive feedback (notshown). The control may also be passive based on prior calibration. Thepositioning system may also have the capacity to register print-headunit 530 relative to a particular position in the plane of substrate 540by utilizing optical feedback. The optical feedback may include adigital camera and processing system for converting the digital imageinto positioning instructions. The positioning system may have anabsolute position resolution of between 10 nm and 10 cm for eachdirection, as appropriate for the application. For instance, for someOLED applications, a positioning resolution of one micron for eachdirection can be employed.

FIG. 6 illustrates a micro-porous discharge nozzle having micro-poreswith tapered sidewalls. Discharge nozzle 680, intervening rigid segments665, micro-porous openings 660, and heating elements 650, correspond toelements 180, 165, 160, and 150 of FIG. 1A, except that the sidewalls ofmicro-pores 660 are tapered. The taper may be engineered so that thewider section of the micro-pore is closer to substrate 690 than thenarrower section. The tapered design can be advantageous because uponactivation of the discharge nozzle and the subsequent dislodgingmaterial, the tapering allows discharge along the direction of the widersection of micro-pores 660. In the exemplary embodiment of FIG. 6, thetaper is shown so that activation of discharge nozzle 680 with heatingelements 650 can increase the fraction of material that flows tosubstrate 690 as compared to micro-pores having straight sidewalls.While the sidewalls of FIG. 6 have a substantially straight taper, onecan utilize any sidewall profile designed to have a larger opening onone end as compared to the other such that the fraction of materialflowing out of the nozzle in one direction or the other is altered.Another example of such a tapered sidewall includes a side that widensmonotonically from one end to the other with a curved profile. Yetanother profile for rigid segments 665 can be a trapezoidal shape.

FIG. 7 shows exemplary micro-pore patterns for use in a micro-porousdischarge nozzle. Shapes 701, 702, and 703 represent exemplary patterns.Complex pixel shape 701 defines a rectangle, complex pixel shape 702 isdefines an L-shape pattern, while complex pixel shape 703 defines atriangle. Other complex pixel shapes, such as ovals, octagons,asymmetric patterns, etc., can also be devised without departing formthe principles disclosed herein. Each of the pixel patterns can compriseone or more micro-pores 704. Such pixel patterns are advantageous indepositing a uniform thin film of material with a micro-porous dischargenozzle that covers a region that is not a simple square or circle.Depositing a film using complex micro-pore patterns can be superior todepositing an equivalent region with multiple depositions using a circleor square micro-pore pattern because deposition by this latter methodyields a film with a non-uniform thickness where the separatedepositions overlap. Additionally, it may not be possible to recreatesmall features in certain shapes (such as the points of a triangle)except by using an impractically small square or circular micro-porepattern.

Referring to FIG. 7, each micro-pore 704 can have a width of w1. In anexemplary embodiment, w1 is between 0.1 .mu.m to 100 .mu.m. Eachmicro-pore pattern can have a width w2 of between 0.5 .mu.m and 1 cmdepending on the number, size, and spacing of the micro-pores. Theconversion of the complex micro-pore pattern into a correspondingpattern of deposited material on a substrate by the discharge apparatuscan depend on the number of micro-pores in the discharge apparatus, thediameter of each micro-pore, the spacing of the micro-pores, the shapeof the micro-pore sidewalls, and the distance between the dischargeapparatus and the substrate. For example, the discharge apparatus canhave complex micro-pore pattern 701, each of the micro-pores can have adiameter (w1) of 1.0 .mu.m, have a center to center spacing of 2.0microns, and have a straight sidewall. The micro-pores can be positionedabout 100 .mu.m from the substrate. It has been found that this approachcan be used to recreate an approximately rectangular pattern ofdeposited material corresponding to complex micro-pore pattern 701.

In one embodiment, a discharge apparatus according to the disclosure canbe used to deposit ink in substantially solid form on a substrate. Theink can be composed of the material to be deposited on the substrate inthe form of particles initially suspended or dissolved in a carrierliquid. The carrier liquid can be organic, for example, acetone,chloroform, isopropanol, chlorbenzene, and toluene, or can be water. Thecarrier liquid can also be a mixture of the materials identified above.One or more of the components to be deposited on the substrate can be anorganic molecular compound, for example, pentacene, aluminumtris-(8-hydroxyquinoline) (A1Q3),N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine(TPD), bathocuproine (BCP), or fac tris(2-phenylpyridine) iridium(Irppy). One or more of the components to be deposited on the substratemay also be polymeric. One or more of the components to be deposited onthe substrate may be inorganic, such as a semiconductor or insulator orconductor. One or more of the deposited materials can be an electroninjection material. One or more of the deposited materials can be anelectron transport material. One or more of the deposited materials canbe light emitting material. One or more of the deposited materials canbe a hole transport material. One or more of the deposited materials canbe a hole injecting material. One or more of the deposited materials canbe an exciton blocking material. One or more of the deposited materialscan be a light absorbing material. One or more of the depositedmaterials can be a chemical sensing material. The deposited materialsmay be used as, for instance, conductors, light emitters, lightabsorbers, charge blockers, exciton blockers, and insulators, in, forinstance, OLEDs, transistors, photodetectors, solar cells, and chemicalsensors.

The properties of the ink can define an important factor in depositingthe film. One of the important performance criteria for the ink can bethe efficient, reliable, and uniform loading of the ink material fromthe chamber into the discharge nozzles. Relevant performance criteriainclude the ability of the ink: (1) to wet one or more of the dischargenozzle surfaces; (2) to be drawn rapidly into the discharge nozzleholes; and (3) to spread rapidly over the area of the discharge nozzlecontaining the discharge nozzle holes. Another important performancecriterion for the ink is the consistent delivery of the desired mass ofmaterial into the discharge nozzle, so the desired amount of material isconsistently deposited each time the discharge nozzle discharges itsmaterial. The ink can be adapted so that the ink is reliably deliveredfrom the chamber orifice to the discharge nozzle with a consistent inkvolume. These adaptations have been carried out by the inventors fortarget inks by designing the physical and chemical properties of the inkliquids and the material dissolved or suspended in the ink. Theseproperties include, but are not limited to, viscosity, thixotropy,boiling point, material solubility, surface energy, and vapor pressure.

In one embodiment, the discharge apparatus according to the disclosedembodiments can be used to deposit metal material on a substrate. Thedeposited metal material can be deposited in substantially solid form.The deposited material can include metal synthesis utilizingorgano-metallic precursor materials dissolved or suspended in a solvent,or metal dissolved or suspended in a solvent. The metal dissolved orsuspended in a solvent may comprise, at least partially, nanoparticles,which can be coated with organic compounds. The metal can be, forinstance, gold, silver, aluminum, magnesium, or copper. The metal can bean alloy or mixture of multiple metals. Such metal material is useful inmany applications, for instance, as thin film electrodes, electricalinterconnections between electronic circuit elements, and passiveabsorptive or reflective patterns. Metal films deposited by thedischarge apparatus can be used to deposit the electrodes and electricalinterconnections utilized in circuits including organic electronicdevices such as OLEDs, transistors, photodetectors, solar cells, andchemical sensors. Organo-metallic or metallic material can be deliveredto the discharge nozzle, and upon activation of the discharge nozzle canbe delivered to the substrate. A reaction converting the organo-metallicmaterial into metallic material can be carried out prior to or duringdelivery of the liquid from the chamber to the discharge nozzle, duringdelivery from the discharge nozzle to the substrate, or followingdeposition on the substrate. When delivering metal material from thedischarge nozzle to the substrate, it is advantageous to utilizenanoparticles because this reduces the energy required to dislodge themetal from the micro-pores. Metal deposited on a substrate utilizing thedischarge apparatus has the advantage of efficiently utilizing materialand employing a deposition technique that may not damage the materialonto which the metal film is deposited, including both the underlyingsubstrate and any other deposited layers.

In another embodiment, the discharge apparatus is used to depositinorganic semiconductor or insulator material in substantially solidform on a substrate. The deposition material can include synthesisutilizing organic and inorganic precursor materials dissolved orsuspended in a carrier liquid, or inorganic semiconductor or insulatordissolved or suspended in a carrier liquid. The inorganic semiconductoror insulator dissolved or suspended in a liquid may be comprised of all,or in part, nanoparticles, which can be coated with organic compounds.The inorganic semiconductor or insulator can be, for instance, group IVsemiconductors (for instance, Carbon, Silicon, Germanium), group III-Vcompound semiconductors (for instance, Gallium Nitride, IndiumPhosphide, Gallium Arsenide), II-VI compound semiconductors (forinstance, Cadmium Selenide, Zinc Selenide, Cadmium Sulfide, MercuryTelluride), inorganic oxides (for instance, Indium Tin Oxide, AluminumOxide, Titanium Oxide, Silicon Oxide), and other chalcogenides. Theinorganic semiconductor or insulator can be an alloy or mixture ofmultiple inorganic compounds. The semiconductor or insulator materialcan be useful in many applications, for instance, as transparentconductors for electrodes and electrical interconnections betweenelectronic circuit elements, insulating and passivation layers, and asactive layers in electronic and optoelectronic devices. When integratedtogether, these layers can be utilized in circuits containing organicelectronic devices such as OLEDs, transistors, photodetectors, solarcells, and chemical sensors.

In another embodiment, precursor or inorganic semiconductor or insulatormaterial can be delivered to the discharge nozzle, and upon activationof the discharge nozzle can be delivered to the substrate. A reactionconverting the precursor material into the desired inorganicsemiconductor or insulator material can be carried out prior to orduring delivery of the liquid from the chamber to the discharge nozzle,during delivery from the discharge nozzle to the substrate, or followingdeposition on the substrate. When delivering inorganic semiconductor orinsulator material from the discharge nozzle to the substrate, it can beadvantageous to utilize nanoparticles for reducing energy required todislodge the material from the micro-pores. Inorganic semiconductor orinsulator material deposited on a substrate utilizing the dischargeapparatus has the advantage of efficiently utilizing material andemploying a deposition technique that may not damage the material ontowhich the film is deposited, including both the underlying substrate andany other deposited layers.

FIGS. 8A and 8B (collectively, FIG. 8) schematically illustrate a dyesublimation printer in accordance with one embodiment of the disclosure.In FIG. 8A, ink droplet 809 comprises ink pigments dissolved orsuspended in a carrier liquid. The carrier liquid can comprise one ormore components, including organic solvents and water. Ink droplet 809is directed to the backside of the discharge apparatus 850. Droplet 809is drawn into micro-pores 840 where the solvent portion of the liquidink evaporates, leaving pigment particles 810 deposited on micro pore840 walls.

Next, and with reference to FIG. 8B, heater 830 can be activated tovaporize pigment particles 810 from micro-pores 840 and discharge thepigment particles from discharge nozzle 825. The discharged pigmentparticles condense on substrate surface 860, forming pixel pattern 870of a printed pigment. Heater 830 can also be used to evaporate anyremaining solvent in pixel pattern 870.

FIGS. 9A and 9B illustrate the use of the discharge apparatus forspatially localized chemical synthesis. In the embodiment of FIG. 9A,reactant gas 910 is flown over discharge nozzle 825. Reactant gas 910can additionally help vaporize and remove evaporated solvents. The gasflow, along with deposition ink 809, can be drawn into the dischargenozzle micro-pores 840.

In FIG. 9B, vaporizable reactant 920 is directed to discharge nozzle 825and pressed through micro-pores 840. Vaporizable reactant 920 mayoptionally contain the suspended particles which form synthesizedmaterial 930. Heater 830 can be activated to heat reactant gas flow 909containing solid ink particles to be deposited. Vaporizable reactant(not shown) from micro-pores 840 can be transported out of the systemusing an effluent gas (not shown). The heat from heater 830 can thenactivate the desired chemical reaction to produce the desired material930 on a substrate 860. In another embodiment, the discharge apparatus850 can be employed as an efficient, spatially localized heatingelement, submerged in either a gaseous or liquid environment in whichheat from heater 830 is used to activate the chemical syntheses process.

In still another embodiment, an ink having dissolved or suspendedparticles in a carrier liquid (not shown) is delivered to dischargenozzle 825. Discharge nozzle 825 comprises micro-pores 840 for receivingthe ink. After the carrier liquid is evaporated, heater 830 heats theparticles deposited on pore walls of the micro-pores 840, where theparticles are vaporized and mixed with ambient gaseous and/or liquidenvironment. In another embodiment the discharge apparatus can beemployed as an efficient, spatially localized heating element, in whichheat from heater 830 is used to activate the chemical syntheses processon a defined area of the substrate.

FIGS. 9C and 9D depict the use of a discharge apparatus as a microreactor. As shown in FIG. 9C, optional reactant gas flow or inkdeposition 909 or vaporizable reactant 911 can be deposited on thebackside of the discharge apparatus 850. Discharge apparatus 850 can beintegrated into a micro-scale chamber with micro-scale chamber valves922 and 924 for controlling the in- and out-flux of gaseous and liquidproducts, reactants, and analytic or synthetic product 970. In FIG. 9C,optional reactant gas flow or ink deposition 909 or vaporizable reactant911 is drawn into micro-pores 840. Heater 830 is activated to heatoptional reactant gas flow or ink deposition 909, or vaporizablereactant 911 from micro-pores 840 and discharge them from dischargenozzle 825. The heat from heater 830 can then activate the desiredchemical synthesis process to produce analytic or synthetic product 970on substrate 860.

In another embodiment, the discharge apparatus can be used to createsub-pixels for displays such as Red, Green, or Blue sub-pixels. Eachsub-pixel can have lateral dimensions from 20 .mu.m to 5 mm wide. Otherdimensions are available without departing from the principles disclosedherein. The subpixels can include one or more films deposited using oneor more of the apparatuses discussed in relation to FIGS. 1A-1D orvariations thereof (e.g., as shown in FIGS. 3-4, or in FIGS. 10-11, asdiscussed further below), referred to here as the “thermal jet” and thecorresponding deposition method as the “thermal jet deposition method.”A plurality of these sub-pixels can be deposited over a substrate toform one or more displays. When multiple displays are deposited on asubstrate, the substrate can be subdivided into individual displays.Deposition using the thermal jet deposition method can be advantageousover shadow masking because shadow masking can require long thin piecesof metal with holes which can twist and bend over large areas and/orwhich can be difficult to keep clean and/or which generate dustparticles.

FIG. 10A is a schematic representation of an exemplary print-head.Referring to FIG. 10A, the exemplary apparatus for depositing a materialon a substrate comprises chamber 1030 for housing ink with containingparticles of material to be deposited on a substrate suspended ordissolved in a carrier liquid. Chamber 1030 includes orifice 1070 and adelivery path from orifice 1070 to a discharge nozzle 1080. Dischargenozzle 1080 is defined by a surface that may contain a plurality ofmicro-porous conduits 1060 for receiving the material communicatedthrough orifice 1070 from chamber 1030. These conduits extend into, butnot through, supporting material 1040 which provides mechanical supportfor the discharge nozzle 1080. Housing 1040 may be joined to the housingfor chamber 1030 using bracket or connecting material 1020.

Chamber activator 1015 also includes a piezoelectric actuator 1015coupled to chamber 1030 for providing pulsating energy to activate theink dispensing mechanism and thereby meter a droplet of the liquid fromchamber 1030 through orifice 1070 towards discharge nozzle 1080. Thepulsating energy can be variable on a time scale of one minute or less.For instance, the piezoelectric actuator 1015 can be energized withsquare pulses having a variable duty cycle and a cycle frequency of 1kHz. Chamber 1030 may contain material required for forming a film usedin the fabrication of an OLED or a transistor. Orifice 1070 isconfigured such that surface tension of the liquid in chamber 1030prevents discharge of the liquid prior to activation of thepiezoelectric ink dispensing mechanism.

Discharge nozzle 1080 may include rigid portions (interchangeably,partitions) 1065 separated by micro-pores 1060. The micro-pores regioncan be composed of a variety of materials, such as micro-porous aluminaor solid membranes of silicon or silicon carbide and havingmicro-fabricated pores. In one embodiment, micro-pores 1060 receive thematerial dissolved or suspended in the liquid and prevent the materialfrom being released again from discharge nozzle 1080 until the medium isappropriately activated. Discharge nozzle 1080 may also comprise a roughsurface (not shown) for receiving the material dissolved or suspended inthe carrier liquid and delivered from chamber orifice 1070. The surfacecan similarly contain the material until the discharge nozzle isproperly actuated. Alternatively, discharge nozzle 1080 may comprise asmooth surface (not shown) for receiving the material dissolved orsuspended in the liquid and delivered from chamber orifice 1070. Thesmooth surface can be adapted to contain the material until thedischarge nozzle is properly actuated. Such adaptations can comprisemodification of the surface chemistry or proper selection of thedischarge nozzle material with respect to the choice of liquid.

In the exemplary device of FIG. 10A, when the discharged droplet ofliquid encounters discharge nozzle 1080, the liquid is drawn intomicro-pores 1060 with the assistance of the capillary action. The liquidin the ink may evaporate prior to activation of discharge nozzle 1080,leaving behind a coating of the suspended or dissolved material on themicro-pore walls. The evaporation of the liquid in the ink may beaccelerated by heating discharge nozzle 1080. The evaporated liquid canbe removed from the chamber and subsequently collected (not shown) byflowing gas over one or more of the discharge nozzle faces.

Depending on the desired application, micro-pores 1060 can providecontainers having a maximum cross-sectional distance W of a fewnanometers to hundreds of microns. The micro-porous region comprisingdischarge nozzle 1080 will take a different shape and cover a differentarea depending on the desired application, with a typical dimension Dranging from a few hundred nanometers to tens of millimeters. Ifdischarge nozzle 1080 is adapted so that the micro-porous region isreplaced by a roughened surface region or a smooth surface region (notshown), the discharge nozzle 1080 behaves in substantially the samemanner, whereby the material delivered in a liquid from the chamber 1030to discharged nozzle 1080 is retained on the surface (by surface tensionthrough proper control of surface and material properties) untilactivation of discharge nozzle 1080. The evaporation of the liquid inthe ink may be accelerated by heating the discharge nozzle. Again, theevaporated liquid can be removed from the chamber and subsequentlycollected (not shown) by flowing gas over one or more of the dischargenozzle faces.

In the exemplary apparatus of FIG. 10A, the relative orientation of thechamber nozzle orifice 1070 and the surface of discharge nozzle 1080 aresuch that the liquid in chamber 1030 can be delivered directly from thechamber orifice 1070 (for instance, by firing a droplet at a controlledvelocity and trajectory out of chamber orifice 1070) onto the dischargenozzle surface. Furthermore, the discharge nozzle surface is alsopositioned such that when activated, the material delivered to thedischarge nozzle surface can flow substantially towards the substrate.In the exemplary embodiment of FIG. 10A, this is accomplished byaligning the discharge nozzle surface to an intermediate angle relativeto both the incoming trajectory of the liquid supplied through chamberorifice 1070 and the angle of the substrate, which would be placed belowthe print-head (shown in FIG. 10B).

Also, in the exemplary embodiment of FIG. 10A, the discharge nozzle isactivated by heater 1050 which is positioned proximal to the dischargenozzle 1080. Nozzle heater 1050 may comprise a thin metal film, composedof, for instance, platinum. When activated, nozzle heater 1050 providespulsating thermal energy to discharge nozzle 1080, which dislodges thematerial contained within micro-pores 1060 allowing the material to flowout from the discharge nozzle. Dislodging the material may includevaporization of the substantially solid ink particles, either throughsublimation or melting and subsequent boiling. In general, one canemploy any energy source coupled to the discharge nozzle capable ofenergizing discharge nozzle 1080 and thereby discharging the materialfrom micro-pores 1060. For example, mechanical (e.g., vibrational)energy may be used.

FIGS. 10B-10E illustrate a method for depositing a film using theprint-head shown in FIG. 10A. The method of FIG. 10B is referred toherein as the thermal surface jet deposition method. Referred to FIG.10B, chamber 1030 is commissioned with ink 1002, comprising particles ofmaterial to be deposited on a substrate, dissolved, or suspended in acarrier liquid. Piezoelectric elements 1015 pulsatingly meter liquid1002 as it travels from chamber 1030 through orifice 1070 to form freedroplet 1001. In an alternative embodiment (not shown), a heater ispositioned in place of piezoelectric element 1015 for pulsatinglyactivating a thermal ink dispensing mechanism and thereby driving atleast a portion of liquid 1002 in chamber 1030 through orifice 1070 toform free droplet 1001. In general, any pulsating energy source thatactivates the ink dispensing mechanism to thereby meter liquid 1002 asit travels through orifice 1070 towards discharge nozzle 1080 can beutilized. The intensity and the duration of each energy pulse can bedefined by a controller (not shown).

Referring to FIG. 10B, discharge nozzle heater 1050 may be activated sothat the discharge nozzle temperature is elevated above ambienttemperature. The heating cycle assists in rapidly evaporating the liquidin the ink after it is deposited on the discharge nozzle. Dischargenozzle heater 1050 may also be activated prior to energizing the inkdispensing mechanism (and discharging ink droplet 1001 from chamber 1030through orifice 1070) or after droplet 1001 lands on discharge nozzle1080.

In FIG. 10C, droplet 1001 travels from chamber orifice 1070 to dischargenozzle 1080, where the ink is drawn into micro-pores 1060. The solventor carrier liquid in ink 1003, which may fill the micro-pores, mayevaporate prior to activation of discharge nozzle 1080, leaving behindon the micro-pore walls the material 1004 that is substantiallysolvent-free and in substantially solid form and which is to bedeposited onto the substrate. This is shown in FIG. 10D. Alternatively,the solvent or liquid 1003 may evaporate during activation of dischargenozzle 1080.

FIG. 10E shows the step of activating nozzle heater 1030 to providepulsating energy to discharge nozzle 1080 dislodges the material inmicro-pores 1060. The intensity and the duration of each pulse can bedefined by a controller (not shown). The activating energy can bethermal energy, but alternatively the energy source can be coupled todischarge nozzle 1080 to energize discharge nozzle 1080 and dischargethe material from micro-pores 1060. For example, mechanical (e.g.,vibrational) energy may also be used for this step. Substrate 1090 canbe positioned proximal to discharge nozzle 1080 to receive the dislodgedmaterial to thereby form thin film 1005.

FIG. 11A schematically illustrates a thermally activated print-headaccording to one embodiment of the disclosure. The apparatus shown inFIG. 11A comprises chamber 1130 for housing ink, chamber orifice 1170and a delivery path from orifice 1170 to a discharge nozzle 1180.Discharge nozzle 1180 includes a surface that containing a plurality ofmicro-porous conduits 1160 for receiving the liquid ink, containingparticles of material to be deposited on a substrate dissolved orsuspended in a carrier liquid, communicated through orifice 1170 fromchamber 1130. Conduits 1160 extend into, but not through, bracket 1142which structurally supports discharge nozzle 1180. Bracket 1142 isjoined to supporting sidewalls 1140 through rotating joints 1141.Sidewalls 1140 may then be connected to a larger frame to form a housingfor chamber 1130 (not shown).

Chamber activator 1110 optionally defines a heater coupled to chamber1130 for providing pulsating energy which activates the ink dispensingmechanism to meter a droplet of the liquid from within chamber 1130through orifice 1170 towards discharge nozzle 1180. As stated, pulsatingenergy can be variable on a time scale of one minute or less. Forexample, the actuator 1110 can be energized with square pulses having avariable duty cycle and a cycle frequency of 1 kHz. Chamber 1130 maycontain material required for forming a film used in the fabrication ofan OLED or transistor. Orifice 1170 can be configured such that surfacetension of the liquid in chamber 1130 would prevent liquid dischargeprior to activation of the ink dispensing mechanism.

Discharge nozzle 1180 may includes rigid portions (interchangeable,partitions) 1165 separated by micro-pores (or conduits) 1160. Themicro-porous region can be composed of a variety of materials, such asmicro-porous alumina or solid membranes of silicon or silicon carbideand having micro-fabricated pores. Micro-pores 1160 receive ink andprevent the material from being released again from discharge nozzle1180 until the medium is appropriately activated. Discharge nozzle 1180may also include a rough surface for receiving the material dissolved orsuspended in the liquid and delivered from chamber orifice 1170. Suchsurfaces can retain the material until the discharge nozzle is properlyactuated. Alternatively, discharge nozzle 1180 may also contain a smoothsurface for receiving the material dissolved or suspended in the liquidand delivered from chamber orifice 1170. Such surfaces can retain thematerial until the discharge nozzle is properly actuated. It should benoted that such adaptations may require modifying the surface chemistryor selecting appropriate discharge nozzles configuration given thesurface chemistry of the liquid.

In FIG. 11A, when the discharged droplet of liquid encounters dischargenozzle 1180, the liquid is drawn into micro-pores 1160 with assistancefrom capillary action and molecular surface tension. The liquid mayevaporate prior to activation of discharge nozzle 1180, leaving behind asubstantially solid coating of the suspended or dissolved particles onthe micro-pore walls 1160. The evaporation of the liquid in the ink maybe accelerated by heating discharge nozzle 1180. The evaporated liquidcan be removed from the chamber and subsequently collected (not shown)by flowing gas over one or more of the discharge nozzle surfaces.

Depending on the desired application, micro-pores 1160 can providecontainers having a maximum cross-sectional distance W of a fewnanometers to hundreds of microns. The micro-porous region comprisingdischarge nozzle 1180 will take a different shape and cover a differentarea depending on the desired application, with a typical dimension Dranging from a few hundred nanometers to tens of millimeters. Ifdischarge nozzle 1180 is adapted so that the micro-porous region isreplaced by a roughened surface region or a smooth surface region (notshown), the discharge nozzle 1180 behaves in substantially the samemanner, whereby the material delivered in a liquid from the chamber 1130to discharged nozzle 1180 is retained on the surface (by surface tensionthrough proper control of surface and material properties) untilactivation of discharge nozzle 1180. The liquid may evaporate prior toactivation of discharge nozzle 1180, leaving behind a substantiallysolid coating of the suspended or dissolved material on the dischargenozzle surface. The evaporation process may be accelerated by heatingthe discharge nozzle. Again, the evaporated liquid can be removed fromthe chamber and subsequently collected (not shown) by flowing gas overone or more of the discharge nozzle faces.

The relative orientation of the chamber nozzle orifice 1170 and thesurface of discharge nozzle 1180 are such that the liquid in chamber1130 can be delivered directly from the chamber orifice 1170 (forinstance, by firing a droplet at a controlled velocity and trajectorythrough chamber orifice 1170) onto the discharge nozzle surface.Discharge nozzle 1180 can be integrated in 1142 so that it can berotated relative to side walls 1140 through 1141. The rotation is usedto reorient the surface of discharge nozzle 1180 so that when activated,the material delivered to the discharge nozzle surface can flowdirectly, or at an angle, towards the substrate.

In FIG. 11A, the discharge nozzle can be activated by a heater. Thedischarge nozzle heater 1150 can be positioned proximal to the dischargenozzle 1180. Nozzle heater 1150 may comprise a thin metal film, composedof, for instance, platinum. When activated, nozzle heater 1150 providespulsating thermal energy to discharge nozzle 1180, which acts todislodge the material contained within micro-pores 1160, which cansubsequently flow out from the discharge nozzle. Dislodging saidmaterial may include vaporization, either through sublimation or meltingand subsequent boiling. Any energy source coupled to the dischargenozzle capable of energizing discharge nozzle 1180 to discharge thematerial from micro-pores 1160 may be used. Confining well 1145 operatesin the same manner disclosed in relation to FIG. 1D.

FIGS. 11B-11E show an exemplary implementation of the print-headapparatus of FIG. 11A. Referring to FIG. 11B, the first step is filingchamber 1130 with ink 1102. The liquid ink may contain materialdissolved or suspended in a liquid and can be deposited as a thin film.Chamber heater 1110 pulsatingly introduces thermal energy into the ink1102 in chamber 1130 and thereby meters at least a portion of liquid1102 through orifice 1170 to form free droplet 1101. In anotherexemplary embodiment (not shown), chamber piezoelectric elements 1115pulsatingly introduce mechanical energy into the ink 1102 in chamber1130 and thereby meter at least a portion of liquid 1102 through orifice1170 to form free droplet 1101. The discharge nozzle heater 1150 may beactivated so that the discharge nozzle temperature is elevated aboveambient temperature. This can assist in rapidly evaporating the liquidin the ink once deposited on the discharge nozzle. The discharge nozzleheater 1150 may also be activated prior to energizing the ink chamber(and discharging ink droplet 1101 from chamber 1130 through orifice1170) or after droplet 1101 lands on discharge nozzle 1180.

In FIG. 11C, droplet 1101 travels from chamber orifice 1170 to dischargenozzle 1180, where the ink is drawn into micro-pores 1160. Liquid in ink1103, which may fill the micro-pores and extend onto the surroundingsurface, with the extent of this extension controlled in part by theengineering of the surrounding surface, may evaporate prior toactivation of discharge nozzle 1180, leaving behind on the micro-porewalls the material 1104 substantially free of solvent. This step of theprocess is illustrated in FIG. 11D. The solvent in liquid 1103 may alsoevaporate during activation of discharge nozzle 1180.

Prior to activating discharge nozzle 1180, the discharge nozzle isrotated 180 degrees relative to sidewalls 1140. As discussed in relationto FIG. 11A, bracket 1142 rotates relative to sidewalls 1140 alongjoints 1141. This rotation brings the discharge nozzle surface closer toand substantially parallel to substrate 1190, so that there is a directpath from the discharge nozzle surface to the substrate. This step ofthe process is shown in FIG. 11E. Thereafter, activating nozzle heater1130 to provide pulsating energy to discharge nozzle 1180 dislodges thematerial in micro-pores 1160. The intensity and the duration of eachpulse can be defined by a controller (not shown). In this exemplaryexample, the activating energy is thermal energy; one can alternativelyemploy any energy source coupled to discharge nozzle 1180 that iscapable of energizing discharge nozzle 1180 and thereby discharging thematerial from micro-pores 1160. Substrate 1190 can be positionedproximal to discharge nozzle 1180 to receive the dislodged material andthin film 1105 can be formed.

FIG. 12 illustrates a method for depositing particles on a substrateaccording to one embodiment of the disclosure. Referring to FIG. 12, instep 1200, liquid ink is provided from a reservoir to the chamber of athermal jet printing device. The liquid ink can be a combination of aliquid carrier and a plurality of ink particles. In step 1210 a desiredquantity of liquid ink is metered from the chamber. A dispenser can beused to meter the desired quantity of liquid ink. The dispenser cancomprise an electromechanical or vibrational device configured to directenergy to the chamber. In an alternative embodiment, the dispensercomprises a heater. In another embodiment, the dispenser comprises apiezoelectric element. Pulsating energy can be provided to the dispenserto meter the desired quantity of ink. In step 1220, the metered quantityof ink is directed from the chamber to a discharge nozzle. The ink canbe directed to the discharge nozzle using gravity feed, forced airconduction or through any conventional means. In step 1230, the liquidcarrier is evaporated to leave behind substantially solid particles ofink.

In one embodiment, the evaporation step is implemented as soon as themetered quantity of ink leaves the chamber. In another embodiment,evaporation commences once the liquid ink has reached the dischargenozzle. In still another embodiment, the evaporation step continuesuntil substantially all of the carrier liquid has evaporated. In step1240, the substantially-solid ink particles are dispensed from thedischarge nozzle and deposited on the substrate in step 1250.

FIG. 13 is a schematic representation of a control system forcontrolling a dispensing device. In FIG. 13, chamber 1330 is in fluidcommunication with reservoir 1399. Reservoir 1399 provides liquid ink tochamber 1330. The liquid ink comprises carrier liquid 1391 and dissolvedor suspended particles 1396. Dispenser 1310 is positioned proximal tochamber 1330 to agitate the chamber and thereby meter a desired quantityof liquid ink from the chamber. Dispenser 1310 can comprise, amongothers, a heater. Dispenser 1310 is in electrical communication withcontroller 1395 through wiring 1353 and 1352.

Controller 1395 comprises processor 1397 and memory 1398. Memory 1398can contain instructions for directing the processor to activatedispenser 1310 in order to meter an exact quantity of liquid ink fromchamber 1330. For example, memory 1398 can comprises a program topulsatingly activate dispenser 1310 in order to dispense a desiredquantity of ink onto discharge nozzle 1380. Controller 1395 may alsoactivate chamber 1330 in order to dispense a desired quantity of inkonto discharge nozzle 1380.

Discharge nozzle 1380 receives the metered quantity of liquid ink fromchamber 1330. Heaters 1348 and 1349 are positioned proximal to thedischarge nozzle 1380 and configured to heat the metered quantity of inkto thereby evaporate substantially all of the carrier liquid 1391,leaving behind substantially solid ink particles. Heaters 1348 and 1349can further heat the substantially solid ink particles and thereby boilor sublime the material, so that discharge nozzle 1380 can dispense inkparticles 1396 towards substrate 1390. As particles 1396 land onsubstrate 1390 and condense they form a substantially solid film.Heaters 1348, 1349 are positioned about discharge nozzle 1380 to helpevaporate liquid carrier 1391 and dispense solid particles 1396.

In the embodiment of FIG. 13, controller 1395 also controls activationand operation of heaters 1348 and 1349 through electric lines 1350 and1351, respectively. Memory 1398 can be configured with instructions todirect processor 1397 to engage and disengage heaters 1348 and 1349 tothereby evaporate liquid carrier 1391 and deposit particles 1396 ontosubstrate 1390.

While the schematic representation of FIG. 13 provides a singlecontroller (i.e., controller 1395), the principles disclosed are notlimited thereto. In fact, a plurality of controllers, with eachcontroller having one or more independent processors and memory circuitscan be used to accurately control the thermal dispensing system. Forexample, a first controller (not shown) can be used to control meteringliquid ink delivered from chamber 1330 by controlling the pulseparameters supplied to dispenser 1310. A second controller (not shown)can be used to control heaters 1348 and 1349. The second controller canbe used to energize the discharge nozzle 1380 to evaporate the carrierliquid. The second controller can receive an input identifying anattribute of the ink. Exemplary attributes of the ink include the ink'sviscosity, thixotropic properties, and molecular weight.

While the principles of the disclosure have been illustrated in relationto the exemplary embodiments shown herein, the principles of thedisclosure are not limited thereto and include any modification,variation or permutation thereof.

1. A method for depositing ink on a substrate, the method comprising:using a pulsating energy having a first frequency to meter a quantity ofink to a discharge nozzle, the ink defined by a plurality of solidparticles in a carrier liquid; receiving the metered quantity of ink atthe discharge nozzle and evaporating the carrier liquid from the meteredquantity of ink to provide a quantity of substantially solid inkparticles; dispensing the substantially solid ink particles from thedischarge nozzle and depositing the substantially solid ink particles onthe substrate; and wherein at least a portion of the substantially solidink particles are converted to a vapor phase during discharge from thedischarge nozzle, directed to the substrate as a vapor, and condense ona surface of the substrate in substantially solid form.
 2. The method ofclaim 1, wherein the step of using the pulsating energy to meter thequantity of ink further comprises heating the quantity of ink with aplurality of heat pulses.
 3. The method of claim 1, wherein the step ofusing the pulsating energy to meter the quantity of ink furthercomprises activating a piezoelectric element to meter the quantity ofink.
 4. The method of claim 3, wherein the piezoelectric element isactivated by providing a pulse of energy at a first frequency.
 5. Themethod of claim 1, wherein the step of dispensing the substantiallysolid ink particles from the discharge nozzle further comprisesproviding a plurality of conduits spanning from an inlet port of thedischarge nozzle to an outlet port of the discharge nozzle, theplurality of conduits receiving the plurality of solid particles and thecarrier liquid at the inlet port and heating the ink to be dispensedfrom the output port in substantially solid form.
 6. The method of claim1, wherein the step of dispensing the quantity of ink from the dischargenozzle in substantially solid form further comprises providing adischarge nozzle having a plurality of conduits separated by a pluralityof partitions, each conduit having an opening surface area W which holdsthe relationship 1/20,000<W/D<¼, wherein D is the inlet port surfacearea of the discharge nozzle.
 7. The method of claim 1, wherein thesolid ink particles are substantially solvent free.
 8. A method fordepositing ink on a substrate, the method comprising: providing liquidink to a chamber, the liquid ink defined by a plurality of suspendedparticles in a carrier liquid; pulsatingly energizing a dispenser tometer a quantity of liquid ink from the chamber to a discharge nozzle,the quantity of liquid ink metered as a function of a frequency of atleast one of a pulse amplitude, a pulse duration or a pulse frequency;receiving the metered quantity of ink at a discharge nozzle, thedischarge nozzle having a plurality of conduits for directing themetered quantity of ink; heating the metered quantity of ink at theplurality of conduits to evaporate the carrier liquid; and dischargingthe plurality of suspended particles from the discharge nozzle onto thesubstrate; wherein the plurality of suspended particles are deposited onthe substrate in substantially solid form.
 9. The method of claim 8,wherein the step of pulsatingly energizing the dispenser results inheating the chamber with a plurality of energy bursts.
 10. The method ofclaim 8, wherein the step of pulsatingly energizing the dispenserfurther comprises energizing a piezoelectric element.
 11. The method ofclaim 8, wherein the step of providing liquid ink to the chamber furthercomprises supplying ink from a reservoir to the chamber.
 12. The methodof claim 8, wherein the step of receiving the metered quantity of ink atthe discharge nozzle further comprises receiving the metered quantity ofink at an inlet to the conduit, transporting the metered quantity of inkthrough the conduit and substantially evaporating the carrier liquid asthe metered quantity of ink is transported through the conduit.
 13. Themethod of claim 8, wherein the step of discharging the plurality ofsuspended particles from the discharge nozzle further comprisesselectively heating the discharge nozzle to discharge the suspendedparticles.
 14. The method of claim 13, wherein the step of heating thedischarge nozzle further comprises pulsatingly heating the dischargenozzle.
 15. The method of claim 8, wherein the step of discharging theplurality of suspended particles further comprises using a piezoelectriceffect on the discharge nozzle to deposit the suspended particles ontothe substrate.
 16. The method of claim 15, wherein using thepiezoelectric effect further comprises mechanically stressing thedischarge nozzle.
 17. The method of claim 8, wherein the step ofpulsatingly energizing the dispenser further comprises controlling thequantity of dispensed ink by controlling at least one of duration,intensity, or frequency of the pulse energy.